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Managing Disk Space

While the cost of storage has dropped incredibly in the past
few years, disk usage is still a valid concern for administrators
seeking to version large amounts of data. Every bit of version history
information stored in the live repository needs to be backed up
elsewhere, perhaps multiple times as part of rotating backup schedules.
It is useful to know which pieces of Subversion’s repository data need
to remain on the live site, which need to be backed up, and which can be
safely removed.

How Subversion saves disk space

To keep the repository small, Subversion uses deltification (or deltified
storage) within the repository itself. Deltification involves encoding
the representation of a chunk of data as a collection of differences
against some other chunk of data. If the two pieces of data are very
similar, this deltification results in storage savings for the
deltified chunk—rather than
taking up space equal to the size of the original data, it takes up
only enough space to say, “I look just like this other piece of
data over here, except for the following couple of changes.”
The result is that most of the repository data that tends to be
bulky—namely, the contents of versioned files—is stored at a much
smaller size than the original full-text representation of that data.
And for repositories created with Subversion 1.4 or later, the space
savings are even better—now those full-text representations of file
contents are themselves compressed.

Note

Because all of the ...

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